An investigation that led to the jailing of a Labor Hero was tainted by protocol violations and the trial's verdict should be nullified to make way for a new probe, the Supreme People's Procuracy said Tuesday.

The Supreme People's Court should annul the verdict against Tran Ngoc Suong, former director of state-run Song Hau Farm in Can Tho, which found her guilty of establishing an illegal slush fund at the collective, said the procuracy, Vietnam's highest prosecutor's office.

In November last year, Suong was sentenced to eight years in jail for running a slush fund and ordered by the Can Tho People's Court to pay back VND4.3 billion (current US$226,853) to the government. Suong was named a Labor Hero by the government in 2000 and honored at the International Federation of Business & Professional Women's Women Inspire Awards in 2002.

A previous trial in August by the city's Co Do District People's Court issued the same sentence after she was found guilty of instructing her subordinates to embezzle more than VND9.1 billion ($480,084) for the off-the-book fund between 2001 to 2007. Suong then lodged an appeal against the verdict, saying it was unlawful and unjust.

The city's court also awarded jail sentences of between two to five years to three officials involved in the case. It suggested prosecutors press charges against Suong for embezzlement as well.

However, the Supreme People's Procuracy said on April 6 there had been shortcomings and procedural violations during Suong's investigation and trial. The agency did confirm that it was right to investigate and charge Suong with the crime, but it disapproved of the way the situation was handled by investigators, prosecutors and the court.

The prosecutor's office said Suong could not be held responsible for some of the fund's sources, including VND2.6 billion ($137.203) that came from the selling of four land plots that her father Tran Ngoc Hoang the farm's former director had bought with state money and the fund between 1993 and 1997.

Loans of more than VND2.2 billion from individuals were also part of the fund but should not be fully included because Suong had paid VND1.5 billion to the state during the investigation, the procuracy said.

The agency also said there was no evidence to back up accusations that the farm had spent VND233 million in bribes to state auditors in 2004, nor was their proof to back up the claim that it had spent nearly VND2.4 billion buying gifts and paying the staff members.

The prosecutor's office said the Co Do District Prosecutor's Office was wrong to suggest Suong be charged for embezzlement.

Since it was put under investigation in 2008, the high-profile case has been controversial.

Former vice president Nguyen Thi Binh called Suong's prison sentence unjust, adding that the slush fund was actually a welfare fund for the collective. Several other high-ranking officials also spoke out in defense of Suong.

Many Song Hau farmers had entered the collective landless and with few prospects, and had since become prosperous, earning Suong their gratitude.

More than 100 members from one of Vietnam's most successful collective farms had written to the Party Unit in Can Tho City after the verdict expressing their wishes to serve jail time in place of Suong.

On the other hand, some people had protested Suong's sentence as being too lenient.